Let's talk about ashes

pbl_ge(5/6)October 15, 2011

So I'm new to the northerly country, and it appears as though we'll be building a lot of fires this winter. Interwebs provide conflicting reports on ashes in the garden. What do you all think? Wood is almost all maple. Soil is alkaline.

Wood ash is primarily Calcium Carbonate which will help reduce the free radical Hydrogen ions in your soil and raise the soils pH. Most all knowledgeable places will tell you to have your soils pH tested before adding any wood ash to that soil.

I'm trying ashes in my vegetable garden (Indiana, heavy clay, ph 7 )At a rate of one large coffee can per 100sq.ft.. Works out about the same as a 5 gal bucket per 1000 sq.ft.. At that rate the ph hasn't changed in 3 yrs. and it appears to help loosen the clay up. I'm trying to raise the potassium, magnesium,trace mineral, levels in the garden. hopefully the link will help you.

myluck, read the link from UConn, and am very confused by the opening lines:

Using Wood Ashes In the Garden!
After the long winter many New Hampshire residents are faced with a different type of problem. What does one do with the wood ashes left from their wood burning stove or fireplace? An average cord of wood, depending on the efficiency of combustion and wood type, will yield approximately twenty pounds of ashes or the equivalent of one five-gallon pail. Over the winter, this can add up to quite an accumulation of wood ashes.

He is saying an average cord will produce approx. 20#s of ash. HUH??? IMO, something's way off in the calculations.

Here I put them into the compost bin with everything else and let them cook with the pile. It hasn't hurt anything and a soil test of the garden soil(veggie) shows that this has not really affected the ph of the soil.

rosiew, I keep this article for the amount applied to the Garden. I laughed when I read about 20#/cord ashes theory. If you want another good laugh, look at the top of the page. "Integrated Pest Management" is in the title box. Is he trying to tell us that people who use wood ashes are pest? There is probably some truth to that. You need a sense of humor when gathering info on the internet.

The wood ash is more calcium oxide (similar to burnt lime) while still dry and calcium hydroxide (like slaked lime) after wetting, thus is even more powerful at first in raising pH. Later sorption of CO2 from the soil atmosphere or open atmosphere converts this to calcium carbonate, similar to ground limestone. A parallel series exists for the potassium, except that its carbonate is still quite soluble and leaches through readily.

Like another poster above, mine go into composting, in my case usually onto piles of oak or pecan leaves having some acidity.

Once upon a time, although not that long ago, there were those that thought (no studies to conform it) that if your compost was made of Oak leaves you needed to add some kind of liming agent, ground limestone or wood ashes, to correct the composts pH.
Today, because of good research, we know that all leaves will be acidic and that finished compost will be neutral without adding any liming agent and that adding things like wood ashes can slow bacterial activity in the compost pile.
Every good online article I have seen over the years has stated fairly clearly before adding wood ashes, or any other liming agent, test your soils pH to see if it needs that CaCo3. An imbalance of Ca and Mg in your soil can create as many problems as a low pH will since plants need a balance of Ca and Mg to properly utilize either one.

I was more thinking in terms of the fresh, though dry and brown, oak leaves helping neutralize the ashes rather than needing the liming. You can easily see the ability of these leaves to yield abundant organic acid. Put a bit of any strong alkali solution onto oak-leaf debris and you will see the black organic matter ("humic acid") react and dissolve right out.

Compost is the result of biological activity not a chemical reaction. Put any strong alkali soluton in the mix of materials to make compost and that strong alkali will slow down the biological digestion, if not kill off the bacteria that will do that, at least according to most of the good, solid, research I have seen.

I occasionally contribute to these perennial wood ash threads, being an inveterate wood burner/ash thrower on alkaline soils.

There are two schools:

- those who burn wood and toss buckets of ashes on their flower beds, vegetable gardens, out on the snow over their lawns, on the driveway to melt snow, and merrily add buckets of the stuff to their compost piles, and have empirical experience from years of ash heaving from hundreds of cords of wood.

- those who study the issue and decide that it isn't a good idea.

I am firmly in the first camp. And last year, I did report, here on this august forum, that I had finally found a deleterious result when, using poor ash-heaving technique, I ended up with 2-3 inches of ash on a patch of lawn that was anchored in two inches of soil over rock - thus a fairly high ratio - and some of that grass died. It all grew back the next summer, but in the interest of scientific study, there ya go - avoid this.

I'm not convinced that using ash on the driveway to melt the ice and snow is a good idea either, because you end up with a muddy/ashy slurry on your shoes that can be hard to wipe off on a door mat. Not to mention the reaction of the SO when these tracks make it onto the rug.

But aside from that, I heave ash in the front flowers, the back flowers, around the trees, out over the lawn, into the compost ..... actually, it depends on how deep the snow is, and when it starts to melt off, I follow the drifts so that I'm sure the cinders land on something wet.

As with everything you read on the internets, your milage may vary. If you're concerned, you might try throwing ash in some out-of-the-way spot and see for yourself what happens.

And a shout out to all my ash-throwin' homeys - new season upon us, work on the 3 gallon toss techniques - wrist action and all that. Our motto: Remember - Stand Up Wind

"Put any strong alkali soluton in the mix of materials to make compost and that strong alkali will slow down the biological digestion."
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Simply not so. Put a small to moderate amount of alkali, strong or not, into a pile of acidic tannin-rich leaf or wood material and it will speed up biodegradation. The plants make that acidic material to slow down biological attack (by parasitic fungi or bacteria, or herbivorous animals, mainly invertebrates). It persists in the dead leaves. The protective action may not be the acidity per se (tannic acids act more as a protein coagulant for animal herbivory I think) but neutralizing, liberating, and perhaps eventually leaching these organic acids away has to help decomposition. One tans leather with these tannic acids to inhibit microbial decomposition.

As an added note, those of us who live in regions of fire-maintained forests have to laugh a bit at the notion that a frequent light application of ashes somehow causes any harm to soil or plants, especially on naturally acidic soils though limey soils included.

New, old house, neglected abused soil from previous owners. Very saline, high phosphorous and K+, pH is fine, I'm making progress in the main plot. Finally getting to where they threw the ashes and dog poo. What do I do with the ashy soil? What can I grow in it until I can get enough compost for everywhere? One site suggested lavender, suggestions?